Hearing aid mold

ABSTRACT

A mold for earpiece devices either to connect an earphone to the ear canal or to act as a cover or plug thereof, allowing to prevent the development of ear diseases comprising: a mold placed in the ear canal and/or ear shell, adjusted to its shape, and whose external border is in direct contact with the user&#39;s skin; and a metallic piece with biocide properties, located inside the mold at a distance close to the border thereof; wherein the metallic piece is adjusted from inside the mold ( 10 ) to the shape of the external contour thereof, allowing that only the mold is in direct contact with the skin, and encompassing all the zones where contact is produced.

This application claims benefit of U.S. Provisional Ser. No. 61/560,410,filed 16 Nov. 2011 and which application is incorporated herein byreference. To the extent appropriate, a claim of priority is made to theabove disclosed application.

FIELD OF APPLICATION

The present invention is related with the application of metals withbiocide properties, in particular copper, in the medical industry givenits antimicrobial properties. In particular, the present invention isrelated with molds for earpiece devices, which are in direct contactwith the ear canal, and in which a metallic piece is inserted,preferentially having a plate shape with biocide properties, which canalso be used in any earpiece device, such as earplugs for noisereduction, earplugs to avoid water entry, audio earphones, wirelesstechnology earphones such as bluetooth technology, earplugs, earmuffs,audio protective devices, headsets, in such a manner that the deviceenables efficient prevention of ear diseases such as infectious externalear otitis in their users and potentially preventing other pathologies.

BACKGROUND

Copper is a metal widely distributed in nature. The efficacy of theantimicrobial activity of products based in copper has motivated thedevelopment of different studies aimed to know the mechanisms involvedin this activity, as well as evaluating potential industrialapplications for this metal.

Phyllis J Khun, a bacteriologist, demonstrated in 1983 the antimicrobialproperties of copper. In 2008, the US Environmental Protection Agency(EPA) published a bibliographical review on the different properties ofcopper and its benefits in human health, among which its bacteriostatic,fungistatic bactericide, fungicide, and sanitation and disinfectionpowers are emphasized.

The effectiveness of products based in copper as antimicrobial agentshas motivated scientists to design new applications in the health area.

The mechanism associated with the antibacterial activity of copper isstill uncertain. Some studies suggests that copper in highconcentrations can have a toxic effect on bacteria due to its tendencyto alter between its different oxidation states, the generation ofhydroxyl radicals, highly reactive, and being able to damage essentialbacterial biomolecules. These radicals could act by substitution ofessential ions conducting to interference in: protein synthesis;enzymatic activity or functions of the bacterial cell membrane. On thecontrary, toxicity of host cells caused by DNA damage seems unlikely. Infact, there are observations suggesting that copper can protect hostcells from DNA damage caused by hydrogen peroxide.

The molds for earpieces, such as earplugs for aquatic sports or thoserelated to acustic trauma, audio devices and earphones in general (forexample retro-auricular earpieces, intracanal earphones and completelyin canal (CIC) earphones), are essential part of the devices, since themold is the one which is adjusted to the ear of the user. For example,in the case of hypoacusia, it is required that earpiece molds are customfabricated considering each user. Also, these earpieces allow acousticsealing of the ear canal and acoustic modification of the aural signal.When fabricating the molds, the following aspects must be considered:comfort degree, aesthetical appeal, operative easiness, and patienttolerance to the materials. Different variations can be made to theearpiece mold in order to produce a lighter, more comfortable and moresuitable earpiece depending on its application. Even molds containinginside an aural device can be fabricated. Nevertheless, sometimes usersof earpieces have allergic reactions to the material of a particularmold and the mold must be replaced by a different material.

Otitis externa has been described as one of the complications associatedto the prolonged use of earpiece devices, and particularly to the use ofearphones and earplugs, since in order to avoid the feedback effect, theearpiece mold must completely seal the ear canal, which contributes tothe development of a series of additional problems such as lack of aircirculation, perturbation in earwax evacuation and facilitation ofprotective earwax being dissolved by humidity, thus making the skin ofthe ear canal more susceptible of infections caused by bacteria orfungus. Therefore, patients with hypoacusia are earphone users anddevelop otitis externa, whom while being in treatment for the infectionmust stop the use of the earphone, which results in deterioration oftheir sensorial capacity and their quality of life.

A solution to the previously mentioned problems is described in thedocument US 2004/0161445, which describes an earphone or an earphonecomponent to be positioned in the ear canal, which comprises a biofilminhibitory coating. The coating comprises an inorganic condensatemodified by some organic groups on the base of coating compositions,including a hydrolyzed or a pre condensed of one or more compounds whichcan be hydrolyzed with at least one substituent which cannot behydrolyzed, wherein at least one portion of the organic groups of thecondensate include fluorine atoms and/or silver or copper colloidscontained in the coating.

A similar solution is described in document US 2004/0179709, whichdescribes at least one membrane of a miniature transducer comprising, atleast in part, an hydrophobic and or oleophobic and or biofilm inhibitorcoating, which due to the thickness of the coating is less than 10 μm,thus it does not affects significantly the auditory features of thetransducer, and prevents the degradation of the transmission featuresdue to humidity, or damages caused by humidity of the transducer.Additionally, the coating can contain copper or silver colloids, andpreferentially comprises silver ion colloids.

Although the previously cited documents describe the use of copper ionsto inhibit the formation of a biofilm in earphones, it is clearly seenthat both documents disclose coatings made from compounds which can havecopper ions in its compositions. Nevertheless, using copper ions in thecoating composition carries different drawbacks, such as:

In the first place, copper ions cannot be separated, which are the onesexerting the antimicrobial activity, to mix them with the polymer in themold, and thus, they have to be released in a solution to allow them toexert their action mainly to bacterial membranes. Cu²⁺ ion, being freeor bonded to the polymer, will not be able to free itself from thepolymer since if the bond is covalent, it will be extremely difficult tofree and exert its antibacterial action.

In second place, EPA, which is the organization certifying theantimicrobial copper properties, only approved metallic copper as havingthe specific features described in the present application, thereforethe effectiveness of ionic copper is not proved.

In third place, using copper ions present in coatings can produceharmful effects to the user's skin, by being the coating in directcontact with the skin, which can produce contact dermatitis and greencoloring of the skin.

In consequence, it can be seen that using ionic copper in compoundsdestined for earphone mold coatings does not allow preventing in ansufficiently effective manner the formation of a biofilm, and thus, itneither does prevent effectively the presence of infections; which couldgenerate further possible adverse effects on the users, produced by thedirect contact of the copper and skin.

In this way, there is a need in the field of the invention to provide amold for earpiece devices allowing to prevent, in an effective manner,potential infections, producing a positive effect in preventing otitisexterna in users and allowing at the same time, avoiding direct contactof the metal with the skin, in order to avoid adverse effects to theuser.

In order to overcome the problems described, a mechanism is presented inwhich the copper exerts its antimicrobial properties in earpiece devicescomprising a metallic piece with biocide properties, preferentially madeof copper, allowing to prevent in an effective way potential infections,producing a positive effect in preventing otitis externa in the user.These earpiece devices can be adjusted to the shape of the ear canal orto the ear shell, and the metallic piece is located inside, avoidingdirect contact between the metallic piece and the skin. The metallicpiece can be a plate and/or similar which is adjusted, from inside themold, to the shape of the external contour of the same, covering all thezones wherein the surface of the mold is in direct contact with theskin, allowing at the same time that only said mold is in direct contactwith the skin of the user.

In this way, the described earpiece device allows solving in aneffective manner the deficiencies described in the state of the art byproviding earpiece devices comprising a metallic piece inside, avoidingdirect contact between said metallic piece and the skin, allowing at thesame time the adherence of pathogenic strains to the surface of themold, of bacteria as well as fungus, thanks to the properties that saidmetallic piece provides, avoiding potential infections, and producing apositive effect in preventing otitis externa in a user.

BRIEF DESCRIPTION OF FIGURES

FIG. 1 shows a scheme of a retroauricular earphone, common in theprevious art, indicating the parts comprising it: mold (1), elbow (2)and earphone (3).

FIG. 2 shows a scheme of the retroauricular earphone mold of FIG. 1,including a metallic piece inside.

FIG. 3 shows a scheme of a retroauricular earphone mold of open moldtype, known as open fit, including a metallic piece inside.

FIG. 4 shows a scheme of an earphone mold for ear shell, of full shelltype, known as full shell, including a metallic plate inside.

FIG. 5 shows a scheme of an earphone mold of half shell type, includinga metallic plate inside.

FIG. 6 shows a scheme of a canal type earphone, including a metallicplate inside.

FIG. 7 shows a scheme of a CIC type earphone mold, including a metallicplate inside.

FIG. 8 shows a comparison between the adherence of Stapylococcus aureususing an initial inoculum of 1.8×10³ CFU/ml, for different materialsused as mold for earphones, including a copper plate inside or lackingthe copper plate.

FIG. 9 shows a comparison between the adherence of Pseudomona aeruginosaATCC 28753 using an initial inoculum of 4.2×10³ CFU/ml, for differentmaterials used as mold for earphones, including a copper plate inside orlacking the copper plate.

FIG. 10 shows a comparison between the adherence of Candida albicansATCC 10231 using an initial inoculum of 3.6×10³ CFU/ml, for differentmaterials used as mold for earphones, including a copper plate inside orlacking the copper plate.

FIG. 11 shows a comparison between the adherence of Aspergillus nigerusing an initial inoculum of 9.4×10⁴ CFU/ml, for different materialsused as mold for earphones, including a copper plate inside or lackingthe copper plate.

DETAILED DESCRIPTION OF THE INVENTION

As can be seen from the figures attached to this application, thepresent invention corresponds to a mold for eapiece devices either toconnect an earphone to the ear canal or to act as a cover or plugthereof, allowing to prevent in an effective manner potentialinfections, producing a positive effect in preventing otitis externa ina user, comprising:

-   -   a device (10) which is placed in the ear canal and or in the ear        shell, adjusting its shape, and whose external border is in        direct contact with the user's skin; and    -   a metallic piece (11) with biocide properties, placed inside the        mold at a distance close to the border thereof;    -   wherein the metallic piece is adjusted from inside the mold (10)        to the external contour shape thereof, allowing that only the        cover of the device is in direct contact with the skin, and        encompassing all the zones where contact is produced.

Said metallic piece (11) with biocide properties can be made of copperor silver in pure state, or an alloy or combination thereof.Nevertheless, in a preferred embodiment of the invention, the metallicpiece is only made of copper.

Also, the metallic piece is preferentially a metallic plate (11) whichis placed at a distance close to the external border of the mold (10),which can be at a distance between 0.1 mm to 2 mm, it was proven that itcan also be between 0.3 mm to 10 mm and has a better effect if thethickness of the copper plate is higher. On the other hand, the metallicplate (11) can have different thickness, between 0.1 mm and 3 mm.

In alternative embodiments of the invention, the material used for thefabrication of the external mold (10) is selected among acrylic, siliconor UV sensitive polymers, vinyl, polyethylene, plastics, polyurethane,elastomeric polymers, PVC, or mixtures thereof. Nevertheless, the moldfor earpiece devices described can use any type of external material forthe fabrication of an external mold (10), as long as it complies withthe functions of the mold and device previously mentioned.

On the other hand, given the features of the metallic piece (11), whichis adjusted to the shape of the border of the external surface of themold (10), the mold for earpiece devices can be used in different typesof devices, such as for example, molds for earphones as described inFIGS. 1 to 7, or other devices such as earplugs for aquatic sports,plugs related to acoustic trauma or audio devices in direct contact withthe ear canal.

Regarding the capacity of avoiding formation of a biofilm in theexternal surface of the mold, there are bibliographical recordsindicating the effects of copper as an antimicrobial agent, for copperwithout any coating as well as copper mixed with other materials,nevertheless, there is not information about the effects of copper beingcoated by different materials which can be used in fabricating molds forearpiece devices, from where it is inferred that one of the mechanismsof antimicrobial action is that the copper ions (which are the onesexerting the reducing power) are transferred or diffused through thematerial of the mold.

FIGS. 8 and 11 show that the adherence of microorganisms to the mold,for different materials, after 4, 8 and 12 hours of contact between themicroorganism and the mold (silicon, acrylic, and UV sensitive polymer)is strongly diminished when using a copper plate inside the mold,finding in some cases up to 100% for each of the materials tested, whichwithout question shows the effect of inserting a copper plate inside themold and wherein said plate is completely covered with the materialsconforming said earpiece device, such as silicon, acrylic and UVsensitive polymer or mixtures of these materials.

Different assays using different thickness of the biocide metallic piece(from 3 to 10 mm) were performed, showing that to a higher volume of thepiece is a higher biocide effect, having the material of the devicealways covering this piece.

Additional results obtained in the development of this work, allowed theinventors to note interesting properties of the different materials usedin the fabrication of earpiece molds: silicon, acrylic and UV sensitivepolymer. Thus, considering the last one by itself (without a copperplate) the UV sensitive polymer was able to produce a lower adherence ofall the studied microorganisms. This action was increased when a copperplate was included in the fabrication, transforming the evaluatedmaterial in the best evaluated material in our study, therefore, thereis a synergic effect by adding a copper plate to this type of mold (UVsensitive polymer), which is due to the inherent properties of thematerial, for example, density and its insulating properties, whichfavors that the copper diffuses through the material and exerts itscapacity as donor and receptor of electrons, derived from its highoxidation-reduction potential, and thus, exerting its antimicrobialaction.

1. A mold for earpiece devices, either to connect an earphone to the ear canal or acting as a cover or plug thereof, allowing to prevent development of ear diseases, comprising: a mold placed in the ear canal and/or ear shell, adjusted to its shape, and whose external border is in direct contact with the user's skin; and a metallic piece with biocide properties, located inside the mold at a distance close to the border thereof; wherein the metallic piece is adjusted from inside the mold (10) to the shape of the external contour thereof, allowing that only the mold is in direct contact with the skin, and encompassing all the zones where contact is produced.
 2. A mold for earpiece devices according to claim 1, wherein the metallic piece is close to the external border of the external mold at a distance between 0.1 mm and 2 mm.
 3. A mold for earpiece devices according to claim 1, wherein the metallic piece is selected from a group consisting of: a copper piece, a silver piece, an alloy thereof or a combination of said pieces.
 4. A mold for earpiece devices according to claim 1, wherein the metallic piece is a metallic plate having a thickness between 0.1 mm and 3 mm.
 5. A mold for earpiece devices according to claim 1, wherein the mold can be used for earphones, earplugs for aquatic sports, plugs related to acoustic trauma, or earpiece devices in direct contact with the ear canal.
 6. A mold for earpiece devices according to claim 1, wherein the material used for the fabrication of said earpiece devices is acrylic, silicon, UV sensitive polymers, vinyl, polyethylene, plastics, polyurethane, elastomeric polymers, and PVC or mixtures thereof.
 7. A mold for earpiece devices according to claim 1, wherein the material used for the fabrication of said earpiece devices is a UV sensitive polymer and has inside a copper piece. 